Overflow tube

Garold Bliss · Jan 23, 2011

1/22/11
I am recoring a 1938 F20 radiator no overflow tube when I got it. What is the thread & how high is the tube in the tank?

Jim350 · Jan 23, 2011

Don't know about that radiator but most are in the neck.

Challenger · Jan 23, 2011

If it is a pressurized system, the overflow needs to be in the radiator neck above the spring seal on the radiator cap. Even in non-pressurized systems, I would place the overflow as high as possible.

Tom Fleming · Jan 23, 2011

couple of quick notes. The F-20 is NOT pressurized, it is thermosyphon. secondly, the overflow is soldered into the tank, or at least that is how I did mine. I used either 5/16" or 3/8" (can't remember) steel brake line to redo my rad.

I am a bit confused about the "thread" question. I will have to measure the protrusion I used on my tank. If I were to estimate, I would say 2", but I really would like to measure. My F-20 is stored for the winter, and I won't be there for a week or two.

I am sure that Nebraska Cowman or 36F30 can answer off the top of their heads, or someone can check.

Oldiron29 · Jan 23, 2011

Garold, I no you can get new ones from Rice Equipment. I have removed broken ones and replace. The Originals I believe was thin wall like brake line and it is treaded into the cast top tank with a fitting. There is a smaller tube soldered into the top of lower tub that raise about 3" up into top tank this sets the water level. I can't remember the tread size but I have used 1/4" black iron pipe and treaded the pipe to fit cast.
I think I used 1/8" copper for top tub.
I copyed one I removed in size and lenght.
Alot of work to get it correct! Most guys put a plug in the hole. oldiron29

rustred · Jan 23, 2011

basically you want it as high as possible , just from memory i would say 1" from top. this way the rad coolant will be kept at its highest level, for thermosyphon to be efficient. i am quite sure the tread is 3/8 npt. just like a piece of black pipe as you dont want thin wall because it will just rust out in no time.

Anonymous-0 · Jan 23, 2011

I got mine from Alderson Tractor. It's precut to the right length (2 pieces) with the fitting that screws into the tank. Chase the threads in the tank. Easy fix.

Overflow tube

Garold Bliss

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Jim350

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Challenger

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Tom Fleming

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Oldiron29

Well-known Member

rustred

Well-known Member

Anonymous-0

Well-known Member

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